Catherine McKenna, Minister of Environment and Climate Change and MP for Ottawa Centre, in an interview on June 26, 2016

Not all hydrofluorocarbons (HFCs) are created equal. Some are more harmful than others. On average, HFCs are thousands of times worse for global warming than carbon dioxide. Not “tens of thousands” as McKenna claimed.

FactsCan Score: Misleading

Pollution landed on the agenda during the Three Amigos Summit this summer with the leaders of Mexico, the United States and Canada.

Catherine McKenna, Canada’s environment minister, put a spotlight on hydrofluorocarbons, or HFCs for short, in a few media interviews during the summit. These are among the ozone-depleting substances the Montreal Protocol was designed to reduce. McKenna claimed they are “tens of thousands of times more polluting than carbon dioxide.”

Is that hyperbole or fact? Before assessing the minister’s statement and what’s meant by “polluting,” we need a little history.

Everything you wanted to know about HFCs (just kidding – only the basics)The Montreal Protocol was originally set up as an international response to scientific findings that chlorofluorocarbons (CFCs) were punching a hole in our atmosphere’s protective ozone layer. This was due to the chemicals’ ability to persist at high altitudes. CFCs were commonly used as refrigerants, but thanks to the international treaty, they were replaced by hydrochlorofluorocarbons, which were in turn replaced by HFCs. HFCs aren’t stable at high altitudes, leading some to link their use to signs of healing in the ozone layer.

However just because HFCs don’t harm the ozone doesn’t mean they’re harmless. Tom Baker, professor and Canada Research Chair at the University of Ottawa’s Center for Catalysis Research and lnnovatíon, explained that once concerns about depleting the ozone were addressed, environmental scientists began to worry about the impact of HFCs on global warming.

Global warming is caused by greenhouse gasses (GHGs) in the atmosphere that trap heat. A chemical’s global warming potential (GWP) is a measure of how much heat the gas can trap relative to other GHGs (CO2 has a GWP of 1). So if a gas has a higher GWP than 1, then compared to CO2, it has a greater ability to trap heat in the atmosphere.

We’re going to assume that when McKenna said HFCs are more “polluting” than CO2, she meant they have a larger GWP – or greater capacity to trap heat in the atmosphere – than C02. So are HFCs “tens of thousands of times” more polluting than carbon dioxide?The simple answer is that they can be. According to Baker, it really depends on the HFC in question. Some HFCS have a very high GWP and are tens of thousands of times worse that C02, while others are not nearly so harmful. For example, HFC-23 is an unwanted byproduct of the production of HCFC-22, which is used to produce Teflon. It has a GWP of 12,700. Contrast that with HFC 1234yf, which has a GWP of less than 1. This can replace HFC-134 (GWP=1300) in car air conditioners.

David Fahey, co-chair of the Scientific Assessment Panel of the Montreal Protocol, said that HFCs currently in use have an average GWP of about 2,300 – meaning they’re 2,300 times stronger than CO2 at trapping heat in our atmosphere over the period of 100 years.

The total use of HFCs is growing globally, and if the current mix of HFCs is unchanged, increasing demand could result in HFC emissions of up to 8.8 gigatons of CO2 equivalent per year by 2050. While, according to our experts, C02 is a far larger contributor to global warming than HFCs, Stephen Anderson, director of research at the Institute for Governance and Sustainable Development, warned it’s hard to exaggerate the damaging impact of HFCs.

(The good news is that a new generation of HFCs are being created and tested. These new refrigerants have significantly reduced GWPs, which means in theory you can keep both your food and the planet cool.)

Verdict

How do we rate McKenna’s statement that HFCs are “tens of thousands of times more polluting than carbon dioxide”?

If we define “polluting” as the ability of a gas to trap heat, then the statement can be true for some HFCs. In general, HFCs do have a higher ability than C02 to trap heat in the atmosphere. However, the HFCs in use average out to be about 2,300 times more polluting than C02, which is not tens of thousands. It’s thousands.